What is the idea behind all of the songs at the end of the hagada [כי לו נאה, חד גדיא, אדיר הוא, אחד מי יודע]? What are they doing there??
The Egyptians believed in many gods - "polytheism" in the vernacular. During the seder we relate the countless miracles as to show that there is a "seder" to the miracles. They all come from One Source and weren't random events. We say the "dayenu" to show that even though we appreciate the many miracles individually, we know where they all came from. There are four sons but they all have a spot around the table because there is a unifying force in their lives.
At the end of the seder we go through the many middos tovos of Hashem in a "seder" of the aleph beis [אדיר הוא], His many servants in the "seder" of the aleph beis [כי לו נאה כי לו יאה]. If there is a "seder" there is a "mesader". We demonstrate how all of the numbers relate to his one-ness [אחד מי יודע], and how all events, even seemingly meaningless ones such as the purchase of a kid for 2 zuz by an anonymous father, ultimately lead to the slaughtering of the angel of death at the end of days and the revelation of Hashem's sovereignty over the earth [חד גדיא].
In the words of HaRav Homnick at the end of his wonderful hagada Marbeh Li-saper -
ביום מורכב, של עם מורכב, בעולם מורכב, הנברא ממחשבה מורכבת של הקב"ה. והכל חוזר להיות אחד. זהו סדר ליל הפסח יום ט"ו
[Based on Hagadas Marbeh Li-saper]
Li-zchut my beloved friend, Rebbe David Shukrallah ben Rachel and his whole family for bracha and hatzlacha in everything!
